No, to remain compatible with x86 32, you cannot add more registers without all sorts of fun problems. Also, since AMD wanted to remain perfectly 32bit compatible, no, no more registers for 32bit apps. Trever On Fri, 2005-02-04 at 18:45 -0500, Chip Turner wrote: > Roland McGrath <roland@xxxxxxxxxx> writes: > > > Unlike other architectures with 32-bit and 64-bit flavors, where the > > biggest change in 64-bit binaries is using twice as much space for a lot of > > things, the x86-64 architecture also has twice as many registers as the > > 32-bit x86 and so 64-bit compiled code tends to perform noticeably better. > > Aren't those registers available to 32bit apps, though, should the > compiler choose to make use of them? > > Chip > > -- > Chip Turner cturner@xxxxxxxxxx > Red Hat, Inc. > -- "Magazines all too frequently lead to books and should be regarded by the prudent as the heavy petting of literature." -- Fran Lebowitz